RALEIGH, N.C. — A criminal investigation triggered by complaints from North Carolina inmates that they were forced to rub habanero hot sauce on their genitals has focused on two prison guards.

N.C. Department of Public Safety spokeswoman Pamela Walker said Friday that agents from the State Bureau of Investigation had opened a formal criminal investigation into inappropriate conduct by two correctional officers at Sampson Correctional Institution. The move comes after the SBI agents conferred with a local prosecutor about possible criminal charges in the case, Walker said.

Prison administrator Lafayette Hall was placed on paid as the investigation began earlier this month. Walker said Hall had since announced that he will retire.

Lead correctional officer Anthony Johnson has resigned. Correctional officer David P. Jones remains on paid leave.

In July, six inmates from Sampson sent a hand-written letter to the U.S. District Court in Greensboro complaining that staff had forced them to perform numerous humiliating acts for the entertainment of guards, including stripping nude and pretending to have sex.

The medium-security facility houses about 500 male inmates in Clinton, which is about 60 miles southeast of Raleigh.

The inmates reported being forced to gulp a super-hot “Exotic Hot Sauce” purchased off the Internet and slather it on their testicles, resulting in painful blisters. Inmates also said they were forced to grab and kiss wild snakes while working on a road crew and throw captured bunnies into oncoming traffic.

Those who performed for the guards were rewarded with preferential work assignments, food, cigarettes and beer, the inmates alleged. Both tobacco and alcohol are banned in North Carolina’s prisons.

In their letter, the inmates ask for the court’s assistance in finding lawyers to help them file a lawsuit against the state and said they feared retaliation from the staff at the prison.

It is not immediately clear if the inmates have a lawyer.

Walker said the prison system first learned of the allegations through internal grievances filed by the inmates, not from the letter to the court.